What is WSDL?

Web Services Description Language (WSDL) is a format for describing a Web Services interface. It is an XML file that describes the technical details of how to implement a web service, more specifically the URI, port, method names, arguments and data types.

Since WSDL is XML, it is both human-readable and machine-consumable, which aids in the ability to call and bind to services dynamically. It is a way to describe services and how they should be bound to specific network addresses.

WSDL has three parts defined as below:

  • Definitions – Generally expressed in XML and include both data type definitions and message definitions that use the data type definitions. These definitions are usually based upon some agreed upon XML vocabulary.
  • Operations – Describes actions for the messages supported by a Web service. There are three types of operations:
    • One way – Messages sent to Web service does not require response.
    • Request/Response – Proper response is sent to Client after request is been served by Web service.
    • Notification – Messages sent to multiple receivers subscribed to Web services.
  • Service bindings – Describes connection of port types to a port. A port is defined by associating a network address with a port type. A collection of ports defines a service. This binding is commonly created using SOAP but other forms may be used like CORBA Internet Inter-ORB Protocol (IIOP), DCOM, .NET, Java Message Service (JMS), or WebSphere MQ to name a few.


J2EE 12


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